the very higher echelons of roman government. what happens is that constantine has a vision. >> in the dream, a cross appears on the sun. the sun was very important to constantine, anyway. he had a thing about helios and very often represented himself with the sun god. but the intrusion of the cross was... was something new, and below this vision was an... was an inscription, were the words "by this, conquer," en touto nike. and he interpreted this dream to mean that, by this symbol of the cross, he could defeat his... his archenemy at the battle of the milvian bridge and become sole emperor. and so he had his-- so the story goes-- he had his soldiers paint the cross on their shields. constantine won the battle of the milvian bridge, became the sole emperor of the roman empire, and then, in a dramatic shift of geopolitics, relocates the center of roman rule from the eternal city, rome, to a new city, constantinople. >> narrator: to reunite a divided empire, constantine moved the capital from rome to a more strategic location, the